How to make polyurethane foam crust thicker
If we talk about the crusting phenomenon in the process of foaming, it can be divided into many kinds, and here I will talk about how to make soft and hard foam crusting and self-crusting these three kinds first.
To make the hard foam crust thicker, the approach is as follows.
1, the appropriate use of water, or increase the point of the whole skin agent.
2, the use of excessive filling way, can obviously good surface.
3, the use of better polyether can also thicken the skin, mainly to choose the viscosity of moderate polyether, because the polyether viscosity is too low will lead to hard foam crust thin; 4, so that the surface hardness, the appropriate amount of low-molecular polyether can also be added to improve the thickness of the skin. The same polyether, for soft foam, soft foam low molecular weight, choose higher molecular weight of polyether will be improved.
If it is self-skinning foam, there are some solutions.
1、Lower the mold temperature, increase the mold pressure appropriately, but it will bring the problem of difficult to release the mold.
2, increase the amount of physical foaming agent, reduce the amount of water, slow down the foaming time. But winter products will be more fragile, the disadvantages are more obvious, so you can reduce the density or cast more material.
3、Use silicone oil with stronger foam stabilization ability.
4、Add a small amount of additional catalysts to accelerate the skin maturation in the formula, such as glycerin type, potassium acetate, castor oil, triethylene diamine.
